The invention relates to centrifugal pumps, and more particularly to an adjustment device for movement of the rotor assembly to effect adjustment of impeller clearance.
The clearance between the front or rear of an open impeller and the stationary parts effects centrifugal pump performance. Therefore, as known from the prior art, a pump has to have a device to adjust the impeller clearance during the assembly and some times in the field due the wear of the stationary parts.
Usually such adjustment is provided by moving rotor assembly forward toward the suction side or backward away from the suction side. In one known adjustment device, three micrometer screws are located on the flange of the bearing housing, and adjustment is made by turning the screws. This design requires precision turning of each screw to avoid locking of the housing in the frame. The housing also requires a relatively long fit, and the gap between face of housing and face of frame does not provide a rigid contact of these two parts. Therefore, this design can cause misalignment of the pump and motor shafts.
In another known adjustment device, three jacking screws and three bolts provide the impeller adjustment. This arrangement has similar disadvantages in causing possible misalignment of the pump and motor shafts.
In a further known adjustment device, the bearing housing is threaded into the frame and locked in position by three set screws. Adjustment is made by turning the notched flange of the housing. This device requires long housing fit, which significantly reduces the useful area inside the frame.
Accordingly, the problem of adjusting the rotor assembly and resulting clearance of the impeller is solved by the device of the invention.